Fluid detection cable

ABSTRACT

A fluid detection cable is described for use in detecting the presence of leaks in areas where a particular fluid is not desired. Sensing leads in the fluid detection cable have a center conductor that may be surrounded with a non-porous conductive polymer coating that protects the conductors from corrosive fluids. A non-conductive polymer at least partially surrounds the sensing leads so that a fluid transmission path allows fluid to contact the conductive polymer. The non-conductive polymer may be porous to provide a fluid transmission path. Fluid transmission paths may also be structurally formed in the non-conductive polymer. The non-conductive polymer protects the sensing leads from false alarms that would occur if the conductive polymer were to be in contact with non-fluid conductive surfaces. The cable may also include monitor leads that are conductors coated with, or embedded in, non-conductive non-porous polymers.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/000,636 entitled “Fluid Detection Cable” by Donald M. Raymond, DonaldA. Raymond and Jeffrey W. Whitham, filed Nov. 30, 2004, which claims thebenefit of and priority to U.S. Provisional Patent Application Ser. No.60/526,203 entitled “Fluid Detection Cable”, filed Dec. 1, 2003, theentire disclosure of which is hereby specifically incorporated byreference for all that it discloses and teaches.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The present invention pertains generally to fluid detection and, moreparticularly, to the use of cables for detection of the presence offluids.

b. Background of the Invention

Cabled sensors and cables have been used in the detection of thepresence of fluids. In many applications, it is desirable not only todetect the presence of fluids, but also to determine the location of afluid.

The ruggedness and durability of the cable used is important. Forexample, in industrial, commercial or residential applications, movementof people or objects above or near the cables may result in breakage ordisconnection of the cable. Hence, fluid detection cables need to besufficiently rugged to minimize potential breakages or disconnections.

In some cases, placement of a structure or object near or on top of thecable may cause a malfunction of the fluid detection system either witha false detection when no fluid is present, or failure to detect a fluidwhen one is present. Some existing cables have a disadvantage when usedaround metal structures or other conductive materials since contact withconductive surfaces can form a short circuit across the sensing leads ofthe cables which can cause a false alarm in the fluid detection system.In existing fluid detection cables, certain conductive elements (e.g.conductors) of the cable must make contact with the fluid to detect thepresence of the fluid. In some cases the construction of the cable issuch that sensing leads are not disposed to immediately sense smallamounts of fluid. A fluid may be present, but the level of the fluid maybe too low to be in contact with the sensing leads. Hence, these cablesdo not detect fluids until the level of the fluid is sufficiently high.

Fluid detection cables that are too big or that have the wrong shape,may also negatively impact the site where they are installed. Forexample, many round fluid detection cables have a diameter of ¼ inch ormore. Installation of such cables below a carpet or other floor coveringcreates a trip hazard or at a minimum an unsightly bump.

Another problem with previous fluid detection cables is that the size ofthe cable makes it difficult to install the cable in tight places. Forexample, in the construction of a building, it may be desirable toinstall fluid detection cables directly adjacent to or along the bottomof a wall or in other tight spaces. Existing cables are too large, orthe wrong shape, and thus are not suitable for use.

Installation of fluid detection systems with cables into environmentswhere equipment, floor coverings, or other structures are already inplace may be difficult or impossible, due to the size and the shape ofthe cable, and the size and shape of the connecters.

Another problem with existing fluid detection cables is that when a leakor other contact of the cable with fluid occurs, it is necessary to drythe cable in order for the system to properly function again. Manycables are constructed with hygroscopic materials, i.e., materials thatabsorb moisture, or act as a wick to draw in and retain fluids. Dryingof these cables to return them to the normally dry state required forfluid detection may require removal of the cable from the installed sitefollowed by heating or blowing the cable for a period of time until themoisture has evaporated. Removal and reinstallation of the cable from aninstalled site may be difficult and time consuming. In some situationsthe cable can be dried without removing it, but the drying process istime consuming and may damage the cable by heating it. Also, some fluiddetection cables require a fastener to secure the cable. Such fastenersmust be placed at regular intervals. Other fluid detection cables mustbe glued to the floor. Such fastening of the cables with certain shapesand sizes may be necessary for proper function, but it makes removal anddrying time consuming and difficult. When the cable is fastened to asurface, the use of large or expensive connectors at the ends of thecable makes cutting the connectors from the ends of the cable in orderto remove it by pulling it through the fasteners difficult and costly.

Further, existing fluid detection cables and connectors requireexpensive materials. As a result, the cost of a fluid detection systemis high, especially for residential applications or other applicationsrequiring relatively low cost.

SUMMARY OF THE INVENTION

The invention may therefore comprise a method of detecting watercomprising: placing a water detection cable comprising two sensingleads, the sensing leads having a center conductor surrounded by aporous non-conductive polymer, the porous non-conductive polymerproviding an insulating layer surrounding the conductor, adjacent to asurface that is to be monitored for the presence of water, andmonitoring the water detection cable.

The invention may further comprise a method of detecting watercomprising: providing a water detection cable that has two sensingleads, the sensing leads having a center conductor that is at leastpartially surrounded by a conductive polymer and a non-conductivepolymer shielding that partially surrounds the conductive polymer, thenon-conductive polymer shielding having at least one water transmissionpath that permits water to electrically contact the conductive polymer;installing the water detection cable adjacent to a surface that is to bemonitored for the presence of water; and providing a monitor formonitoring the water detection cable.

The invention may further comprise a method of detecting watercomprising: providing a water detection cable that has two sensingleads, the sensing leads having a center resistive conductor that is atleast partially surrounded by a non-conductive polymer shielding, thenon-conductive polymer shielding having at least one water transmissionpath that permits water to electrically contact the conductor;installing the water detection cable adjacent to a surface that is to bemonitored for the presence of water; and providing a monitor formonitoring the water detection cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a four-conductor flat fluiddetection cable.

FIG. 2 is an oblique view of a four-conductor flat fluid detectioncable.

FIG. 3A is a cross-sectional view of a flat fluid detection cable with aporous non-conductive polymer coating.

FIG. 3B is a cross-sectional view of another embodiment of a flat fluiddetection cable with a porous non-conductive polymer coating.

FIG. 3C is an oblique view of a flat fluid detection cable with a porousnon-conductive polymer coating.

FIG. 4A is an oblique view of another embodiment of a flat fluiddetection cable without a porous non-conductive polymer coating.

FIG. 4B is an oblique view of another embodiment of a flat fluiddetection cable without a porous non-conductive polymer coating.

FIG. 4C is an oblique view of another embodiment of a flat fluiddetection cable with a porous non-conductive polymer cover on at leastone sensing lead.

FIG. 5A is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 5B is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 6A is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 6B is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 7A is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 7B is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 8A is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 8B is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 8C is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 9A is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 9B is a cross-sectional view of another embodiment of a flat fluiddetection cable.

FIG. 10A is a cross-sectional view of another embodiment of a fluiddetection cable.

FIG. 10B is a cross-sectional view of another embodiment of a fluiddetection cable.

FIG. 11A is a cross-sectional view of a multi-conductor embodiment of afluid detection cable.

FIG. 11 B is a cross-sectional view of a multi-conductor embodiment of afluid detection cable.

FIG. 12 illustrates the manner that a fluid detection cable may beconnected to a transmitter through the use of low-cost plugs andreceptacles.

FIG. 13 illustrates the use of a fluid detection cable with plugs,receptacles and control system with transmitter for connecting to aremote monitor.

FIG. 14 illustrates the use of a fluid detection cable in a particularapplication.

FIG. 15 illustrates the use of a fluid detection cable in anotherapplication.

FIG. 16 illustrates the use of a fluid detection cable in anotherapplication.

FIG. 17 illustrates the use of a fluid detection cable in anotherapplication.

FIG. 18 illustrates the use of a fluid detection cable in anotherapplication that includes monitoring leaks from drainage pipes.

FIG. 19 illustrates the use of a fluid detection cable beneath a carpetor other floor coverings.

FIG. 20 illustrates the manner in which a loop can be formed with atight turning radius of the fluid detection cable maintaining flatcontact against a surface to be monitored for fluid detection.

FIG. 21 illustrates the manner in which a bend can be made in the fluiddetection cable for use in an application that requires a tight turningradius.

FIG. 22 illustrates a type of fastener that can be used to fasten afluid detection cable to a surface.

FIG. 23 illustrates another type of fastener that can be used to fastena fluid detection cable to a surface.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a cross-sectional view of a four-conductor flat fluiddetection cable 100. The fluid detection cable 100 includes a firstsensing lead 124. The first sensing lead has a center conductor 110. Thecenter conductor 110 may be made of copper, stainless steel or otherconductive materials including non-metallic conductors, such as graphitefibers. Alternatively, the center conductor may be a resistive material,such as Chromel or other conductive materials that have additives thatincrease the resistance. Resistive conductors enable fluid detectionsystems to determine the location of a fluid as described below.Resistive conductors are available from Bob Martin Company, South ElMonte, Calif. Resistive conductors that have a resistance in the rangeof 2 to 3 ohms per foot are well suited for use in systems that useresistance to determine the location of a fluid. However, resistiveconductors with any desired resistance may be used.

The center conductor 110, shown in FIG. 1, is surrounded by a conductivepolymer 112. The conductive polymer 112 is non-porous and protects thecenter conductor 110 from corrosion in the presence of corrosive fluids.The conductive polymer 112 is coated with a porous non-conductivepolymer 114. The porosity of the porous non-conductive polymer 114allows water and other fluids to penetrate and make electrical or ioniccontact with the conductive polymer 112. The porous non-conductivepolymer 114 also insulates the inner conductive polymer 112 from makingelectrical contact with non-liquid conductive surfaces such as pipes,conductive computer room subfloors, appliances or other conductivesurfaces. Porous polymer jackets for conductors can be obtained fromNorthwire, Inc., Osceola, Wis. and Putnam Plastics, Dayville, Conn.Porous non-conductive polymers provide a fluid transmission path thatpermits fluid to pass through the non-conductive polymer and to makeelectrical contact or ionic contact with a conductive polymer or aconductor that is covered the porous non-conductive polymer and at thesame time the porous non-conductive polymer does not permit solids tomake electrical contact with a conductive polymer or conductor that issurrounded by the porous non-conductive polymer. In other embodiments,the fluid transmission path through the non-conductive polymer may belong continuous slots in a trough formed by the physical structure ofthe non-conductive polymer, so that the fluid transmission path permitsfluids, but not solids, to pass. In the various embodiments of theinvention, each sensing lead may have a porous fluid transmission pathor a structural fluid transmission path or both. The fluid transmissionpath for one sensing lead may differ from the fluid transmission path ofother sensing leads.

Adjacent and joined to the first sensing lead 124, is a first monitorlead 126. The first monitor lead 126 has a center conductor 102 that maybe made of copper or other conductive materials. Conductors used ineither the sensing leads or the monitor leads may be solid or stranded.The conductors may be made of other conductive materials includingconductive polymers, graphite fibers or any conductive material. Thecenter conductor 102 is surrounded by a non-conductive polymer 104. Thenon-conductive polymer 104 acts as a protective insulator for conductor102. Adjacent and joined to the first monitor lead 126 is a secondmonitor lead 128. The second monitor lead 128 has a center conductor 106that is surrounded by a non-conductive polymer 108. Joined and adjacentto the second monitor lead 128 is a second sensing lead 122. The secondsensing lead has a center conductor 116 that is surrounded by aconductive polymer 118. The conductive polymer 118 is surrounded by aporous non-conductive polymer 120. Within this disclosure, polymers maybe any flexible plastic-like or rubber-like material. All polymercoatings or structures in the drawings herein are non-porous unlessspecifically labeled as porous. Polymers used in the various embodimentsmay be made of halogen free material to meet environmental requirementsin certain applications.

One of the advantages that various embodiments of fluid detection cableprovide over existing cables is that these embodiments provide a fluiddetection cable that does not short circuit or falsely sense a fluidwhen in contact with non-liquid conductive surfaces and at the same timeis flat or has a small diameter, can be formed into a tight loop, andcan be installed in, or removed from, tight places. The thickness of thevarious polymer coatings and the size of the conductors of someembodiments of the fluid detection cable, as described, are exemplaryonly, and should not be considered as limiting the claims. In oneembodiment, the thickness of the first conductive polymer layer may be,e.g., 5 mils thick and the outer porous non-conductive polymer coatingmay be, e.g., 5 mils thick. The non-conductive polymer used to insulatethe monitor leads may be, e.g., 20 mil thick. The conductors may bee.g., about 22 gauge or 24 gauge. Using conductors and coatings of thethickness mentioned allows the height of the cable to be approximately0.1 inches or less. The sensing leads and the monitor leads can bearranged in a flat, ribbon configuration, which facilitates the flatnessof the fluid detection cable. Arrangements in which a monitor lead or aspacing member is disposed between the sensing leads eliminates the needto ensure that any fluid in the porous polymer jacket of the sensingleads is dried following contact with a fluid. The monitor leads orspacing member may be wiped dry and thus eliminate the presence ofconductive fluids between the sensing leads. However, any desiredarrangement and/or order can be used in accordance with the invention.For example, other embodiments of the invention may use at least twosensing leads each with an exterior non-conductive polymer coating thatis porous that provides a fluid transmission path. Fluid transmissionpaths may also be structurally formed in the non-conductive polymercoating. Other embodiments may have one or more monitor leads joined inan arrangement with the sensing leads that have a porous non-conductiveouter jacket.

Fluid detection cables are used to detect the presence of leaks or otherfluids using a variety of electronic means, some of which are describedin U.S. Pat. No. 6,144,209, Raymond et al., which is specificallyincorporated herein by reference for all that it discloses and teaches.Examples of the types of systems frequently used to monitor and detectleaks or other fluids are zone systems, distance read (also calleddirect read) and Time-Domain Reflectometry (herein referred to as TDR)systems. In zone systems, the length of the cable may range from a fewfeet to more than 1000 feet. Further, the conductors of the sensingleads need not be resistive in a zone system. The location of the fluidin a zone system is determined by zone rather than trying to pinpoint adistance from the controller to the point of contact of the fluid withthe cable. In distance read systems (sometimes referred to as directread systems), a sensing lead with a resistive center conductor iselectrically connected to a monitor lead at the end of the cablefarthest from the controller. The sensing lead and the monitor lead atthe end of the cable nearest, or internal to, the controller may beconnected to a constant current source in the controller. A secondsensing lead is connected to a second monitor lead at the end of thecable farthest from the controller and the ends of the sensing lead andthe monitor lead nearest, or internal to, the controller may beconnected to a voltage measuring device. Presence of water or otherconductive fluid forms a conductive path from the sensing lead connectedto the current source to the sensing lead connected to thevoltage-measuring device. The distance from the controller to the pointof contact of the sensing leads with a fluid can be calculated byderiving the resistance required to produce the measured voltage andcalculating the length of cable that has the required resistance.Monitor leads may be used as a conductive path for connecting thesensing leads to the controller. Further, monitor leads may be used as ameans of checking the electrical continuity of a cable. Monitor leadsand sensor leads may also be used to carry other desired electricalsignals such as communication and power signals to distributedelectronic devices.

FIG. 2 is an oblique view of the fluid detection cable 100 described inFIG. 1. The fluid detection cable 100 includes a first sensing lead 124that has a center conductor 110. The center conductor 110 is surroundedby a conductive polymer 112. The conductive polymer is coated with aporous non-conductive polymer 114. Adjacent and joined to the firstsensing lead 124 is a first monitor lead 126 that has a center conductor102. The center conductor 102 is surrounded with a non-conductivepolymer 104. Adjacent and joined to the first monitor lead 126 is asecond monitor lead 128 that has a center conductor 106. The centerconductor 106 is surrounded with a non-conductive polymer 108. Adjacentand joined to the second monitor lead 128 is a second sensing lead 122.The second sensing lead 122 has a center conductor 116. The centerconductor 116 is surrounded by a conductive polymer 118. The conductivepolymer 118 is concentrically surrounded with a porous non-conductivepolymer 120.

FIG. 3A is a cross-sectional view of a four-conductor flat fluiddetection cable 300 with a non-conductive polymer outer shielding 322that forms a trough that is capable of collecting fluid. The fluiddetection cable 300 includes a first sensing lead 324. The first sensinglead has a center conductor 310. The center conductor 310 may be made ofcopper, stainless steel or other conductive materials as disclosed abovewith respect to FIG. 1. Alternatively the center conductor may be ofresistive material as described above. The center conductor 310 is atleast partially surrounded by a conductive polymer 312. The conductivepolymer 312 is non-porous and protects the center conductor 310 fromcorrosion in the presence of corrosive fluids. The conductive polymer312 is coated with a porous non-conductive polymer 314. The porosity ofthe porous non-conductive polymer 314 allows water and other fluids topenetrate and make electrical or ionic contact with the conductivepolymer 312. The porous non-conductive polymer 314 also insulates theinner conductive polymer 312 from making electrical contact withnon-liquid surfaces that are conductive such as pipes, conductivecomputer room subfloors, appliances or other conductive surfaces.Adjacent and joined to the first sensing lead 324 is a first monitorlead 330. The first monitor lead 330 has a center conductor 302 that maybe made of copper or other conductive materials. The center conductor302 is surrounded by a non-conductive polymer 304. The non-conductivepolymer 304 acts as a protective insulator for conductor 302. Adjacentand joined to the first monitor lead 330 is a second monitor lead 328.The second monitor lead 328 has a center conductor 306 that issurrounded by a non-conductive polymer 308. The two monitor leads 330and 328 are covered by a non-porous non-conductive cover 326. Thenon-porous non-conductive polymer cover 326 dries easily when wiped thusfacilitating quick and easy drying of an installed cable or anuninstalled cable. Adjacent and joined to the second monitor lead 328 isa second sensing lead 332. The second sensing lead has a centerconductor 316 that is at least partially surrounded by a conductivepolymer 318. The conductive polymer 318 is surrounded by a porousnon-conductive polymer 320. Adjacent and joined to the sensing leads 324and 332 and the monitor leads 330 and 328, is a non-porousnon-conductive polymer outer shielding 322. Any desired arrangement ofthe sensing leads 324 and 332 and the monitor leads 330 and 328 may bemade as disclosed above with respect to FIG. 1.

FIG. 3A further illustrates an optional adhesive strip 334 that isjoined to the non-conductive outer shielding 322. The adhesive strip maybe used to attach the fluid detection cable 300 to a surface. A similaradhesive strip may be used with any of the embodiments of the invention.

In the fluid detection systems described herein and in other systems,the non-conductive porous polymer outer coating of the sensing leadsprotects the cable from short circuits when the cable contactsnon-liquid surfaces that are conductive. The non-porous non-conductiveshielding 322 forms a trough that is capable of collecting fluids.

For detecting conductive fluids such as water, the fluid detection cable300 may be used with a Time-Domain Reflectometry fluid detection system,herein referred to as a TDR system. Additional details relating to theuse of the fluid detection cable in TDR systems are described below.

FIG. 3B illustrates another embodiment of a four-conductor flat fluiddetection cable. The fluid detection cable 340 is similar to the fluiddetection cable 300 disclosed in FIG. 3A, but has certain structuraldifferences. FIG. 3B discloses monitor leads that are surrounded by anon-porous non-conductive polymer outer shielding 352. FIG. 3B furtherillustrates that the conductor 344 of first sensing lead 342 may bepartially surrounded by a non-porous, non-conductive polymer outershielding 352. Further, conductor 344 of the first sensing lead 342 maybe partially surrounded with a first layer of conductive polymer 346 anda second layer of porous, non-conductive polymer 348, which provides aconductive path for water or other fluids to conductor 344. A secondsensing lead 350 may be made substantially the same as the first sensinglead 342.

FIG. 3C illustrates an oblique view of a four-conductor flat fluiddetection cable 300, illustrated in FIG. 3A, having a non-conductivepolymer outer shielding 322 that forms a trough that is capable ofcollecting fluid. The fluid detection cable 300 includes a first sensinglead 324. The first sensing lead has a center conductor 310. The centerconductor 310 may be made of copper, stainless steel or other conductivematerials as disclosed above with respect to FIG. 1. Alternatively, thecenter conductor may be of resistive material as described above. Thecenter conductor 310 is at least partially surrounded by a conductivepolymer 312. The conductive polymer 312 is coated with a porousnon-conductive polymer 314. Adjacent and joined to the first sensinglead 324 is a first monitor lead 330. The first monitor lead 330 has acenter conductor 302 that may be made of copper or other conductivematerials. The center conductor 302 is surrounded by a non-conductivepolymer 304. The non-conductive polymer 304 acts as a protectiveinsulator for conductor 302. Adjacent and joined to the first monitorlead 330 is a second monitor lead 328. The second monitor lead 328 has acenter conductor 306 that is surrounded by a non-conductive polymer 308.The two monitor leads 330 and 328 are covered by a non-porousnon-conductive cover 326. The non-porous non-conductive polymer cover326 dries easily when wiped thus facilitating quick and easy drying ofan installed cable or an uninstalled cable. Adjacent and joined to thesecond monitor lead 328 is a second sensing lead 332. The second sensinglead has a center conductor 316 that is at least partially surrounded bya conductive polymer 318. The conductive polymer 318 is surrounded by aporous non-conductive polymer 320. Adjacent and joined to the sensingleads 324 and 332 and the monitor leads 330 and 328 is a non-porousnon-conductive polymer outer shielding 322. The non-porousnon-conductive shielding 322 forms a trough that is capable ofcollecting fluids. FIG. 3C further illustrates an adhesive strip 334that is joined to the non-conductive outer shielding 322.

FIG. 4A illustrates an oblique view of another embodiment of afour-conductor fluid detection cable 400. In the embodiment of FIG. 4A,fluid detection cable 400 includes a first sensing lead 402 that has acenter conductor 430 that is surrounded by a non-porous conductivepolymer. The center conductor 430 may be a low resistance conductor or aresistive conductor as described above with respect to FIG. 1. A secondsensing lead 404 may be made substantially the same as first sensinglead 402. Fluid detection cable 400 further includes a first monitorlead 406 that has a conductor 432. Conductor 432 may be a solidconductor or a stranded conductor. Adjacent to first monitor lead 406 isa second monitor lead 408 that may be constructed substantially the sameas the first monitor lead. The monitor leads 406, 408 are positionedbetween the sensing leads 402, 404 so that the cable may be easily wipedto remove fluid. However, other embodiments with the various sensing andmonitor leads in different positions with respect to each other arewithin the scope of the invention.

Monitor leads 406, 408 are surrounded by non-conductive polymer outershielding 410. Non-conductive polymer outer shielding 410 provides aconvenient structure for supporting the sensing leads 402, 404 andmonitor leads 406, 408. In the embodiment of FIG. 4A, the non-conductivepolymer outer shielding 410 has a substantially planar bottom-side towhich an optional adhesive strip 434 may be attached. Non-conductivepolymer outer shielding 410 has two sides which are inclined planes 416,418 as showing in FIG. 4A. Inclined planes 416, 418 permit fluid toeasily climb the sides of non-conductive polymer outer shielding 410 andenter troughs 420, 422, 424, 426. Non-conductive polymer covers 412, 414cover a portion of sensing leads 402, 404 so that a fluid transmissionpath is provided through which fluid can pass to make electrical contactwith a portion of the sensing leads 402, 404. Thus, sensing leads 402,404 are partially exposed to any fluid that collects in troughs 420,422, 424, and 426 through small gaps or slots between the non-conductivepolymer outer shielding 410 and the non-conductive polymer covers 412,414. Long continuous slots, i.e. fluid transmission paths, are formedbetween the non-conductive polymer shielding 410 and the covers 412, 414at the bottom of troughs 420, 422, 424, 426. The fluid transmissionpaths allow fluids to electrically contact the sensing leads and, at thesame time, the structure of the non-conductive polymer preventsconductive solids from electrically contacting the sensing leads 402,404. The use of fluid transmission paths that are long continuous slotsin the bottom of troughs 420, 422, 424, 426, formed between thenon-conductive polymer outer shielding 410 and non-conductive polymercovers 412, 414 allows both the non-conductive polymer outer shielding410 and the non-conductive polymer covers 412, 414 to be made of a broadrange of materials that do not need to be porous and which may bemanufactured using a broad ranges of inexpensive manufacturing methods,such as, for example, extrusion, coating, spraying or any method that isdesired for use with the selected non-conductive polymer.

In some applications it may be desirable to detect fluids only when thelevel of the fluid is high enough to climb the inclined planes 416, 418and enter troughs 420, 422, 424, 426. In other applications, a lowerlevel of fluid may be detected by placing fluid detection cable 400face-down, i.e. with troughs 420, 422, 424, 426 facing down.

FIG. 4B illustrates an oblique view of a flat fluid detection cable 440.In the embodiment of FIG. 4B, fluid detection cable 440 includes a firstsensing lead 442 that has a center conductor 470 that is surrounded by anon-porous conductive polymer 468. The center conductor 470 may be a lowresistance conductor or a resistive conductor as described above withrespect to FIG. 1. A second sensing lead 444 may be made substantiallythe same as first sensing lead 442.

Non-conductive polymer outer shielding 450 provides a convenientstructure for supporting the sensing leads 442, 444. In the embodimentof FIG. 4B, the non-conductive polymer outer shielding 450 has asubstantially planar bottom-side to which an optional adhesive strip 474may be attached. Non-conductive polymer outer shielding 450 has twosides which are inclined planes 456, 458 as shown in FIG. 4B. Inclinedplanes 456, 458 permit fluid to easily climb the sides of non-conductivepolymer outer shielding 450 and enter troughs 460, 462, 464, 466.Non-conductive polymer covers 452, 454 cover a portion of sensing leads442, 444 so that a fluid transmission path is provided through whichfluid can pass to make electrical contact with a portion of the sensingleads 442, 444. Thus, sensing leads 442, 444 are partially exposed toany fluid that collects in troughs 460, 462, 464, and 466 through smallgaps or slots between the non-conductive polymer outer shielding 450 andthe non-conductive polymer covers 452, 454. Long continuous slots, i.e.fluid transmission paths, are formed between the non-conductive polymershielding 450 and the covers 452, 454 at the bottom of troughs 460, 462,464, 466. The fluid transmission paths allow fluids to electricallycontact the sensing leads and, at the same time, the structure of thenon-conductive polymer prevents conductive solids from electricallycontacting the sensing leads 442, 444. The use of fluid transmissionpaths that are long continuous slots in the bottom of troughs 460, 462,464, 466, formed between the non-conductive polymer outer shielding 450and non-conductive polymer covers 452, 454 allows both thenon-conductive polymer outer shielding 450 and the non-conductivepolymer covers 452, 454 to be made of a broad range of materials that donot need to be porous and which may be manufactured using a broad rangesof inexpensive manufacturing methods, such as, for example, extrusion,coating, spraying or any method that is desired for use with theselected non-conductive polymer.

In some applications it may be desirable to detect fluids only when thelevel of the fluid is high enough to climb the inclined planes 456, 458and enter troughs 460, 462, 464, 466. In other applications, a lowerlevel of fluid may be detected by placing fluid detection cable 440face-down, i.e. with troughs 460, 462, 464, 466 facing down.

FIG. 4C illustrates an oblique view of a flat fluid detection cable 441.In the embodiment of FIG. 4C, at least one of the sensing leads such assensing lead 445 is at least partially covered with a porousnon-conductive polymer cover such as porous non-conductive polymer cover455. Fluid detection cable 441 includes a first sensing lead 443 thathas a center conductor 471 that is surrounded by a non-porous conductivepolymer 469. The center conductor 471 may be a low resistance conductoror a resistive conductor as described above with respect to FIG. 1. Asecond sensing lead 445 may be made substantially the same as firstsensing lead 443 except that a porous non-conductive polymer cover 445may be used. The porosity of porous non-conductive polymer cover 445provides a fluid transmission path that allows electrical contact of afluid with sensing lead 445.

Non-conductive polymer outer shielding 451 provides a convenientstructure for supporting the sensing leads 443, 445. In the embodimentof FIG. 4C, the non-conductive polymer outer shielding 451 has asubstantially planar bottom-side to which an optional adhesive strip 475may be attached. Non-conductive polymer outer shielding 451 has twosides which are inclined planes 457, 459 as shown in FIG. 4C. Inclinedplanes 457, 459 permit fluid to easily climb the sides of non-conductivepolymer outer shielding 451 and enter troughs 461, 463, 465, 467.Non-conductive polymer cover 453 covera a portion of sensing leads 443so that a fluid transmission path is provided through which fluid canpass to make electrical contact with a portion of the sensing lead 443.Thus, sensing leads 443, 445 are able to be in electrical contact withfluid that collects in troughs 461, 463, 465, and 467 through the fluidtransmission path formed between the non-conductive polymer outershielding 451 and the non-conductive polymer covers 453 or through thefluid transmission path through the porous non-conductive polymer cover455. The fluid transmission paths allow fluids to electrically contactthe sensing leads and, at the same time, the structure of thenon-conductive polymer prevents conductive solids from electricallycontacting the sensing leads 443, 445.

In some applications it may be desirable to detect fluids only when thelevel of the fluid is high enough to climb the inclined planes 457, 459and enter troughs 461, 463, 465, 467. In other applications, a lowerlevel of fluid may be detected by placing fluid detection cable 441face-down, i.e. with troughs 461, 463, 465, 467 facing down.

FIG. 5A is a cross-sectional view of a fluid detection cable 500. Thefluid detection cable 500 includes a first sensing lead 512. The firstsensing lead has a center conductor 508 that is surrounded by a porousnon-conductive polymer 510. The porous non-conductive polymer 510electrically insulates the conductor 508 from electrical contact withnon-liquid surfaces that are conductive but the porosity allowselectrical or ionic contact with fluids. Adjacent and joined to thefirst sensing lead 512 is non-conductive polymer spacing member 506 ofany desired width. The surface of the non-conductive polymer spacingmember 506 may be wiped dry to remove fluids. Adjacent and joined to thenon-conductive polymer spacing member is a second sensing lead 514. Thesecond sensing lead has a center conductor 502. The conductor 502 issurrounded with a porous non-conductive polymer 504. The fluid detectioncable 500 is flat and relatively inexpensive to manufacture. Hence it isespecially well suited for residential and other applications requiringlow cost.

FIG. 5B illustrates a fluid detection cable 520. Fluid detection cable520 is similar to fluid detection cable 500 disclosed in FIG. 5A but hascertain structural differences. A first sensing lead 534 has a centerconductor 522 that is adjacent and joined to a non-conductive polymerspacing member 526 of any desired width. A porous non-conductive polymer524 at least partially surrounds the conductor 522. A second sensinglead 532 may be made substantially the same as the first sensing lead534.

FIG. 6A is a cross-sectional view of a fluid detection cable 600. Thefluid detection cable 600 includes a first sensing lead 616. The firstsensing lead 616 has a center conductor 602 that is surrounded by aconductive polymer 604. The conductive polymer 604 protects theconductor 602 from corrosion when the sensing lead 616 is in thepresence of a corrosive fluid. The conductive polymer 604 is encircledwith a porous non-conductive polymer 606. The porous non-conductivepolymer 606 insulates the conductive polymer 604 from electrical contactwith non-liquid surfaces that are conductive but the porosity allowselectrical or ionic contact with fluids. Adjacent and joined to thefirst sensing lead 616 is non-conductive polymer spacing member 608 ofany desired width. The surface of the non-conductive polymer spacingmember 608 may be wiped dry to remove fluids. Adjacent and joined to thenon-conductive polymer spacing member is a second sensing lead 618. Thesecond sensing lead has a center conductor 610. The conductor 610 issurrounded with a conductive polymer 612 that is encircled with a porousnon-conductive polymer 614. The fluid detection cable 604 is flat andrelatively inexpensive to manufacture. This embodiment also protects theconductors 602 and 610 from corrosive fluids. Hence, it is especiallywell suited for residential and other applications requiring low costwhere corrosive fluids may be present.

FIG. 6B illustrates a fluid detection cable 620. Fluid detection cable620 is similar to fluid detection cable 600 disclosed in FIG. 6A but hascertain structural differences. A first sensing lead 638 has a centerconductor 630 that is adjacent and joined to a non-conductive polymerspacing member 628 of any desired width. A first layer conductivepolymer 632 at least partially surrounds the conductor 630. A secondlayer porous non-conductive polymer 634 at least partially surrounds thefirst layer conductive polymer 632. A second sensing lead 636 may bemade substantially the same as the first sensing lead 638.

FIG. 7A is a cross-sectional view of a fluid detection cable 700. Thefluid detection cable 700 includes a first sensing lead 716. The firstsensing lead 716 has a center conductor 702 that is surrounded by aconductive polymer 704. The conductive polymer 704 protects theconductor 702 from corrosion when the sensing lead 716 is in thepresence of a corrosive fluid. The conductive polymer 704 is encircledwith a porous non-conductive polymer 706. The porous non-conductivepolymer 706 insulates the conductive polymer 704 from electrical contactwith non-liquid surfaces that are conductive and at the same time theporosity allows electrical or ionic contact with fluids. Adjacent andjoined to the first sensing lead 716 is non-conductive polymer spacingmember 708. The surface of the non-conductive polymer spacing member 708may be wiped dry to remove fluids. One or more monitor conductors, suchas monitor conductor 710 may be embedded within the non-conductivepolymer spacing member. The embodiment of FIG. 7A, as well as any of theembodiments that are shown as including monitor wires, can beconstructed without any monitor wires, if desired. Adjacent and joinedto the non-conductive polymer spacing member is a second sensing lead718. The second sensing lead has a center conductor 712. The conductor712 is surrounded with a conductive polymer 720 that is encircled with aporous non-conductive polymer 714. The fluid detection cable 704 is flatand relatively inexpensive to manufacture. This embodiment also protectsthe conductors 702 and 712 from corrosive fluids. The monitor conductor710 may be connected to one of the sensing conductors to provide areturn path for a current. Alternatively, the monitor conductor 710 maybe connected to another electrical signal which if disconnected signalsa break in electrical continuity of the cable.

FIG. 7B illustrates a fluid detection cable 730. Fluid detection cable730 is similar to fluid detection cable 700 disclosed in FIG. 7A but hascertain structural differences. A first sensing lead 748 has a centerconductor 742 that is adjacent and joined to a non-conductive polymerspacing member 738. A first layer conductive polymer 750 at leastpartially surrounds the conductor 742. A second layer porousnon-conductive polymer 744 at least partially surrounds the first layerconductive polymer 750. A second sensing lead 746 may be madesubstantially the same as the first sensing lead 748.

FIG. 8A is a cross-sectional view of a fluid detection cable 800. Thefluid detection cable 800 includes a first sensing lead 816 that has acenter conductor 802. The center conductor 802 is surrounded by anon-porous non-conductive polymer 804. The non-porous non-conductivepolymer inhibits electrical contact of fluid and solids with conductor802 but allows a fluid to be detected by sensing a change in thedielectric at the location of the fluid. The first sensing lead 816 isadjacent and joined to a non-conductive polymer spacing member 806 ofany desired width. The non-conductive polymer spacing member 806 mayoptionally include one or more additional monitor conductors, such asmonitor conductor 814. Adjacent and joined to the non-conductive polymerspacing member 806 is a second sensing lead 818. The second sensing lead818 includes a center conductor 808 that is surrounded by a conductivepolymer 810 that protects the conductor 808 from corrosion. Theconductive polymer 810 is encircled by a porous non-conductive polymer812. The non-conductive polymer is made to form a trough 820 that iscapable of collecting fluid. The trough allows fluids to be collectedbetween the second sensing lead 818 and the first sensing lead 816. Thetrough enhances the effectiveness of the fluid detection cable 800 whenused with TDR systems as disclosed below with respect to FIG. 9A.

FIG. 8B illustrates a fluid detection cable 830. Fluid detection cable830 is similar to fluid detection cable 800, disclosed in FIG. 8A buthas certain structural differences. A first sensing lead 848 has acenter conductor 838 that is adjacent and joined to a non-conductivepolymer spacing member 836 of any desired width. A first layerconductive polymer 840 at least partially surrounds the conductor 838. Asecond layer porous non-conductive polymer 842 at least partiallysurrounds the first layer conductive polymer 840. A second sensing lead852 has a conductor 832 that is surrounded by a non-porousnon-conductive polymer spacing member 836. The non-conductive polymerspacing member 836 forms a trough 850 that is capable of collectingfluid. The non-porous non-conductive polymer inhibits electrical contactof fluid and solids with conductor 832 but allows a fluid to be detectedby sensing a change in the dielectric at the location of the fluid.

FIG. 8C illustrates a fluid detection cable 860. Fluid detection cable860 is similar to fluid detection cable 830, disclosed in FIG. 8B buthas certain structural differences. A first sensing lead 878 has acenter conductor 858 that is adjacent and joined to a non-conductivepolymer spacing member 866 of any desired width. A first layerconductive polymer 870 at least partially surrounds the conductor 858. Asecond layer non-conductive polymer cover 872 at least partially coversthe first layer conductive polymer 870. A least one structural fluidtransmission path for fluid to electrically contact conductive polymer870 is provided between non-conductive polymer cover 872 and non-porousnon-conductive polymer spacing member 866. A second sensing lead 882 hasa conductor 862 that is surrounded by a non-porous non-conductivepolymer spacing member 866. The non-conductive polymer spacing member866 forms a trough 880 that is capable of collecting fluid. Thenon-porous non-conductive polymer 866 inhibits electrical contact offluid and solids with conductor 862 but allows a fluid to be detected bysensing a change in the dielectric at the location of the fluid.

FIG. 9A is a cross-sectional view of a fluid detection cable 900. Thefluid detection cable 900 includes a first sensing lead 920 that has acenter conductor 902 that is surrounded by a conductive polymer 904. Theconductive polymer 904 in encircled in a porous non-conductive polymer906. The sensing lead 920 is adjacent and joined to a non-conductivepolymer spacing member 908. The non-conductive polymer spacing member908 may optionally include one or more monitor conductors 910 and 912.Adjacent and joined to the non-conductive polymer spacing member 908 isa second sensing lead 922. The second sensing lead 902 includes a centerconductor 914 that is surrounded by a conductive polymer 916 thatprotects the conductor 914 from corrosion. The conductive polymer 916 issurrounded by a porous non-conductive polymer 918. The first sensinglead 920 and the second sensing lead 922 are joined to thenon-conductive polymer spacing member 908 and disposed to form a trough924 that is capable of collecting fluid.

In a Time Domain Reflectometry fluid detection system, the presence ofwater or other fluids causes a change in the dielectric constant at thatlocation of the cable. This change in dielectric constant is measured bysending a signal into a first sensing lead, which may be any of thesensing leads 922 and 920, of the cable and measuring the reflectedsignal over a period of time. A second sensing lead acts as a groundreference. The reflected signal measurement at each point in timecorresponds to a location along the length of the cable. If water orother fluids are in contact with the sensing leads of the cable, areflection corresponding to the location of the liquid will occur. Noreflection will occur from locations where no fluid is present. In a TDRsystem, the fluid need not be conductive, but the reflectioncorresponding to a location in contact with a conductive fluid will havea different amplitude and otherwise differ from a reflection resultingfrom a non-conductive fluid. The sensitivity of the TDR system to thechange in dielectric constant is enhanced by an electrically conductivepath from the first sense lead 922 to the second sense lead 920.Further, the formation of a trough 924, or fluid collecting channel, bythe non-porous non-conductive polymer spacing member 908, enhances thesensitivity of the TDR fluid detection system by increasing the amountof fluid and associated dielectric constant in electrical contact withthe two sensing leads 922 and 920. In other words, the fluid acts as adielectric material that causes a reflected wave in the detection cable.The delay of the reflected pulse is indicative of the location of thefluid. The amplitude of the reflected wave is indicative of the type offluid. For example, water contains more ions than petrochemicals. Waterwill cause a larger reflected pulse, as explained below. Presence of anelectrical short circuit between the sense leads of a fluid detectioncable, such as by unintentional contact with a metal object, such as theside of a cooler or dishwasher, will cause a false detection in priorart liquid detection cables. Use of a porous non-conductive polymer 906and 918 surrounding the sense leads 922 and 920 of the fluid detectioncable prevents false detections caused by short circuiting of the senseleads as a result of an unintentional contact with a non-liquidconductive surface.

In another application, various embodiments of the fluid detection cablemay be used to detect the presence of a fluid in a dissimilar fluid. Thepresence of conductive fluids that are in contact with sensing leads ofvarious embodiments of the fluid detection cable can be distinguishedfrom the presence of non-conductive fluids by measuring the amplitude ofthe reflections. Reflections from locations in contact with conductivefluids will have a reflection with greater amplitude than reflectionsfrom locations in contact with non-conductive fluids. For example, in afuel tank, a thin layer of water may accumulate at the bottom of thetank. The fluid detection cable 900 may be disposed at the bottom of thetank and because of the flatness of the cable and the trough 924 formedby the non-conductive polymer spacing member 908 and the sensing leads920 and 922, a quantity of water will be collected in the trough 924.The water can be sensed, using a conductive and resistive measurement,or using a TDR system to measure a different dielectric constant at thelocation of the cable that is in contact with water. Other embodimentsof the fluid detection cable as disclosed above may be used with a TDRsystem.

FIG. 9B illustrates a fluid detection cable 930. Fluid detection cable930 is similar to fluid detection cable 900 disclosed in FIG. 9A but hascertain structural differences. A first sensing lead 950 has a centerconductor 932 that is adjacent and joined to a non-conductive polymerspacing member 938. A first layer conductive polymer 934 at leastpartially surrounds the conductor 932. A second layer porousnon-conductive polymer 936 at least partially surrounds the first layerconductive polymer 934. A second sensing lead 952 may be madesubstantially the same as the first sensing lead 950.

FIG. 10A is a cross-sectional view of a non-planar embodiment of a fluiddetection cable 1000. The fluid detection cable includes a first sensinglead 1004. The first sensing lead 1004 has a center conductor 1016surrounded by a conductive polymer 1018. The conductive polymer 1018 issurrounded by a porous non-conductive polymer 1020. The fluid detectioncable further includes a two-conductor monitor lead 1002. Thetwo-conductor monitor lead 1002 has a first conductor 1012 and a secondconductor 1010. The first conductor 1012 and the second conductor 1010are electrically insulated and surrounded by a non-conductive polymer1014. Disposed at a midpoint of the two-conductor monitor lead 1002 andjoined to the two-conductor monitor lead 1002 is the first sensing lead1004. A second sensing lead 1008 that is constructed substantially thesame as the first sensing lead 1004 is joined to the two-conductormonitor lead on the side opposite from the first sensing lead 1004. Theporous non-conductive polymer on the sensing leads protects the sensingleads from electrical contact with non-liquid surfaces that areconductive. For example, the fluid detection cable could be used insidea metallic conduit.

FIG. 10B illustrates a fluid detection cable 1030. Fluid detection cable1030 is similar to fluid detection cable 1000 disclosed in FIG. 10A buthas certain structural differences. A first sensing lead 1034 has acenter conductor 1036. A first layer conductive polymer 1048 at leastpartially surrounds the conductor 1036. A second layer porousnon-conductive polymer 1040 at least partially surrounds the first layerconductive polymer 1048. The first sensing lead 1034 is adjacent andjoined to a non-conductive polymer spacing member 1044. A second sensinglead 1038 may be made substantially the same as the first sensing lead1034.

FIG. 11A illustrates another embodiment of a fluid detection cable 1100.Fluid detection cable 1100 includes a first sensing lead 1104. The firstsensing lead has a center conductor 1112 that is surrounded by aconductive polymer 1114. The conductive polymer 1114 is surrounded by aporous non-conductive polymer 1116. The fluid detection cable furtherincludes a second sensing lead 1102 constructed substantially the sameas the first sensing lead. The fluid detection cable 1100 includes aplurality of monitor leads. A first monitor lead 1106 has a centerconductor 1108 surrounded by a non-conductive polymer 1110. Othermonitor leads are constructed substantially the same as the firstmonitor lead. The first sensing lead 1104 and the second sensing lead1102 are joined to the monitor leads.

In larger systems, low resistance conductors may comprise a leader cableto electrically connect the fluid detection cable to the control system.The leader cable is not used to detect the presence of fluids andtherefore need only have low resistance conductive members (e.g.conductors). In such systems it may be desirable to have multiplesections of fluid detection cable. Such a system may use multiple leadercables connected to multiple fluid detection cables. The system mayfirst determine the section or sections of cable that are in contactwith fluid. Then the distance from the controller to the fluid may bedetermined as disclosed above. Multiple sections of fluid detectioncable 1100 may be connected so that some of the monitor leads of a firstsection of cable act as leader cables for a second section of cable. Themonitor leads of the second section of cable act as leader cables forsubsequent sections of cable. Thus, instead of installing multiple fluiddetection cables with multiple leader cables, a single fluid detectioncable 1100 may be installed in sections, with the multiple monitor leadsacting as leader cables to subsequent sections. The fluid detectioncable 1100 with multiple monitor leads may be constructed in anon-planar embodiment as shown in FIG. 1100, or the sensing leads andmonitor leads may be joined to form a flat cable. In either case theouter coating of porous polymer surrounding the sensing leads protectsthe cable from false alarms through an electrical short circuit of thesensing leads when in contact with a conductive non-liquid surface.

FIG. 11B illustrates a fluid detection cable 1120. Fluid detection cable1120 is similar to fluid detection cable 1100 disclosed in FIG. 11A buthas certain structural differences. A first sensing lead 1124 has acenter conductor 1132 that is adjacent and joined to a non-conductivepolymer 1130. A first layer conductive polymer 1134 at least partiallysurrounds the conductor 1132. A second layer porous non-conductivepolymer 1136 at least partially surrounds the first layer conductivepolymer 1134. A second sensing lead 1122 may be made substantially thesame as the first sensing lead 1032.

FIG. 12 illustrates the use a fluid detection cable 1216 in multiplecable system. A detector 1200 may have a plurality of jacks including afirst jack 1206. A fluid detection cable 1216 has a connector 1218 thatis plugged into jack 1206 of the detector. The detector may have asecond jack 1204. Another cable that is a first leader cable 1214 may beplugged into a second jack 1204. The detector may have a third jack1202. A second leader cable 1210 that has a first connector 1208 may beplugged into the third jack 1202 and a second connector 1212 that may beused to connect to another fluid detection cable or a leader cable. Thejacks provide a simple and easy manner of connecting fluid detectioncables and leader cables to the detector 1200.

FIG. 13 illustrates the use of a fluid detection cable in a wirelesssystem 1300. The wireless system 1300 has a detector/transmitter 1302connected to an antenna 1309 and one or more jacks including a firstjack 1308 and a second jack 1310. A fluid detection cable 1304 that hasa connector 1306 may be plugged into the first jack 1308 of thedetector/transmitter 1302. The wireless system 1300 may have a secondcable which may be a leader cable 1314 that has a first connector 1312.The first connector 1312 may be plugged into the second jack 1310 of thedetector/transmitter 1302. The leader cable 1314 has a second connector1316 that may be used to connect to another fluid detection cable or aleader cable. The wireless system further includes a monitor 1318 thathas an antenna 1320 and is connected to the detector/transmitter via awireless connection 1322. A wireless system may be well suited forapplications where installation of a leader cable is not desired suchas, for example, in finished buildings where no provision has been madeto install additional cables.

FIG. 14 illustrates the use of a fluid detection cable 1402 in acommercial or industrial application with a cooler 1400. It may bedesirable to attach the fluid detection cable to the cooler 1400 at aheight so that the fluid detection cable is not in contact with a floorwhich may get wet during mopping. Thus, a level of water high enough topotentially damage the cooler or other equipment will be detected, but athin film of water from cleaning, mopping, or condensation will notcause a false alarm.

FIG. 15 illustrates using a fluid detection cable 1504 in an applicationnear a water heater 1500. The application may include a detector 1502that has a jack 1508. The fluid detection cable has a connector 1506that may be plugged into the jack 1508 of the detector 1502. A leak nearthe water heater can be detected using the fluid detection cable and adetector. The cable may form a loop surrounding an area to be monitor sothat, when the perimeter of the fluid extends to the loop of cable, itis detected. This configuration allows immediate detection of a waterheater leak before major damage occurs. The fluid detection system mayalso be connected so as to turn off valve(s) automatically which wouldbe well suited for applications where a building is left unoccupied forperiods of time.

FIG. 16 illustrates the use of a fluid detection cable 1612 in anapplication near a dishwasher 1600. The fluid detection cable 1612 has aconnector 1610 that may be plugged into a coupler 1608. The porouspolymer jacket surrounding the sensing leads of the fluid detectioncable 1612 prevents false fluid detections from contact with the metaledges of the dishwasher. A leader cable 1604 may have a first end with aconnector 1606 that may be plugged into the coupler 1608. A secondopposite end of the leader cable 1604 may be connected to a monitor1602. The flexibility and flatness of the fluid detection cable 1612 andthe leader cable 1604 make them easy to install in this type ofapplication. Leader cables and corresponding jacks may be pre-installedinside walls prior to hookup of appliances, thus facilitatinginstallation of fluid detection cables at the time appliances areinstalled.

FIG. 17 illustrates the use of a first fluid detection cable 1710 thatis adjacent and beneath a water pipe 1714. A second fluid detectioncable 1722 may be adjacent to the bottom flow plate of a wall and nearto the basement floor 1716. A detector/transmitter 1708 may be connectedto the first fluid detection cable 1710 and to a second fluid detectioncable 1722. The detector/transmitter may have antenna 1706 that isconnected to a remote first monitor 1700 and antenna 1702 via a wirelessconnection 1704. The detector/transmitter may transmit through housewiring 1718 to a second monitor 1720. Small leaks may thus be detectedbecause the water will flow to the under side of the pipe and contactthe fluid detection cable. Such configurations allow detection of leaksinside walls or at other remote locations. Larger leaks can be detectedmore quickly using this arrangement of the fluid detection cable and analarm can be sounded so that actions such as shutting a supply valve canbe taken to minimize damage. Electronically controlled valve(s) may beconnected to the monitor so that when a leak is detected the monitorcauses the valve(s) to shut or close.

FIG. 18 illustrates the use of a fluid detection cable 1802 in anapplication near a drainpipe. The fluid detection cable is connected toa monitor 1800 and may be disposed on the upper surface of a flow plate1804. The fluid detection cable may pass through a hole 1808 in a stud1806 and then again be disposed on the upper surface of the flow plate1804 that is below the drainpipe 1810, thus allowing the detection ofleaks from a drain pipe inside a wall or at other remote locations. Thefluid detection cable 1802 may form a perimeter around a floor drain1812 as depicted in FIG. 18 such that if the floor drain 1812 is blockedand water backs up, the water will contact the fluid detection cable1802 and the fluid can be detected.

FIG. 19 illustrates the use of a fluid detection cable 1904 in anapplication where the cable is installed beneath a carpet 1902. Thefluid detection cable may have a connector 1906. The connector 1906 mayplug into a coupler 1908. A monitor 1900 may be connected to a leadercable 1912 that has a connector 1910 at the end farthest from themonitor. The connector 1910 may plug into the coupler 1908 and providean electrical connection from the monitor 1900 to the fluid detectioncable 1904 through connector 1906. The use of inexpensive connectorscombined with the flat fluid detection cable 1904 facilitates theinstallation and removal of the cable beneath the carpet 1902 andeliminates bumps in the carpet 1902. Leader cables, such as leader cable1912, may be pre-installed for more convenient construction andinstallation.

FIG. 20 illustrates the manner in which a loop 2000 can be formed withthe fluid detection cable. Existing fluid detection cables are notconstructed in a manner that allows a tight turning radius. The tightturning radius and flat ribbon construction of the various embodimentsof fluid detection cables disclosed herein permits the formation of aloop. The flatness or small diameter of the fluid detection cable andthe tight turning radius allow the lengths of the cable extending fromthe loop to be placed substantially flat on a surface thus minimizingany gap between the cable and the surface that is being monitored forfluids. A larger loop may also be made that provides a spare length ofcable that may be utilized if it is necessary to cut off a connectorfrom the cable for removal or repair.

FIG. 21 illustrates a bend radius 2100. The construction, flatness andsize of the various embodiments of fluid detection cables allow thesecables to be installed in applications that require a tight turningradius.

FIG. 22 illustrates one embodiment of a holder 2200 that may be used toinstall the various embodiments of the fluid detection cable disclosedherein. A hole is formed in holder 2200 that may be used with a nail,screw, bolt or other fastening device to fasten the cable to a surface.

FIG. 23 illustrates another embodiment of a holder 2300 that may be usedto install the various embodiments of the fluid detection cabledisclosed herein. The holder 2300 has an adhesive back 2302 that may beused to hold the cable to a surface in applications where it isundesirable to penetrate the surface with a fastening device.

Hence, the various embodiments of the fluid detection cable disclosedprovide a cable with numerous advantages. The non-conductive polymershielding that at least partially surrounds the conductive polymersand/or conductors provides a fluid detection cable that does not shortcircuit when in contact with non-liquid conductive surfaces and at thesame time permits fluids to make electrical contact with the sensingleads. The conductive polymer jacket surrounding the conductors invarious embodiments of the fluid detection cable protects the conductorsfrom corrosion due to contact with corrosive fluids. The size andflatness of the various embodiments of the fluid detection cable make iteasy to install and remove, especially in applications that require thefluid detection cable to be installed in tight places, locationsrequiring tight bends in the cable, and/or beneath carpet or other floorcoverings. The size and shape of the various embodiments of the fluiddetection cable disclosed is such that low cost industry standardconnectors, jacks, tools and accessories may be used to connect, installand use the various embodiments of the fluid detection cable providing asignificant advantage in residential or other applications that requirelow cost. Various embodiments of the fluid detection cable may comprisematerials that facilitate the use of resistive measurement fluiddetection systems or TDR systems to determine the location of the fluid.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

1. A water detection cable comprising: a first sensing lead having aconductor that is at least partially surrounded by a continuousnon-braided, non-conductive polymer covering that is porous to water,said continuous, non-braided, non-conductive polymer covering that isporous to water providing an insulating layer at least partiallysurrounding said conductor; a non-conductive polymer spacing memberadjacent and joined to said first sensing lead; and a second sensinglead having a conductor that is at least partially surrounded by acontinuous, non-braided, non-conductive polymer covering that is porousto water, said continuous, non-braided, non-conductive polymer coveringthat is porous to water providing an insulating layer at least partiallysurrounding said conductor, said second sensing lead disposed adjacentand joined to said spacing member.
 2. The water detection cable of claim1 wherein said non-conductive polymer spacing member is joined to saidfirst sensing lead and said second sensing lead so as to form a troughthat is capable of collecting water.
 3. A water detection cablecomprising: a first sensing lead that has a conductor that is at leastpartially surrounded by a conductive polymer and a continuous,non-braided, non-conductive polymer covering that is porous to waterthat at least partially surrounds said conductive polymer, saidcontinuous, non-braided, non-conductive polymer covering that is porousto water providing an insulating layer at least partially surroundingsaid conductive polymer; a non-conductive polymer spacing memberadjacent and joined to said first sensing lead; and a second sensinglead that has a conductor and is at least partially surrounded by anon-conductive polymer, said non-conductive polymer having a thicknessand a dielectric constant that permits the presence of water to bedetected by detecting a change in the dielectric constant at thelocation of said water, said second sensing lead and said first sensinglead adjacent and joined to said spacing member so as to form a troughthat is capable of collecting water.
 4. The water detection cable ofclaim 3 wherein said non-conductive polymer of said second sensing leadand said non-conductive polymer spacing member are formed from the samematerial.
 5. A water detection cable comprising: a first sensing leadthat has a center conductor that is at least partially surrounded by aconductive polymer and a non-conductive polymer that at least partiallysurrounds said conductive polymer, said non-conductive polymer providingan insulating layer at least partially surrounding said conductivepolymer; a non-conductive polymer spacing member adjacent and joined tosaid sensing lead; a second sensing lead that has a center conductor andis surrounded by a non-conductive polymer, said non-conductive polymerhaving a thickness and a dielectric constant that permits the presenceof water to be detected by detecting a change in the dielectric constantat the location of said water, said second sensing lead and said firstsensing lead adjacent and joined to said spacing member so as to form atrough that is capable of collecting water; and a non-conductive polymercover that partially covers said conductive polymer of said firstsensing lead such that water transmission path that allows water toelectrically contact said conductive polymer of said first sensing leadis provided between said non-conductive polymer cover and saidnon-conductive polymer spacing member.
 6. A method of detecting watercomprising: placing water detection cable comprising two sensing leads,said sensing leads having a conductor at least partially surrounded by acontinuous, non-braided, non-conductive polymer covering that is porousto water, said continuous, non-braided, non-conductive polymer coveringthat is porous to water providing an insulating layer at least partiallysurrounding said conductor, adjacent to a surface that is to bemonitored for the presence of water; monitoring said water detectioncable; and generating a signal upon detection of water.
 7. A method ofdetecting water comprising: providing a water detection cable that hasat least two sensing leads, said sensing leads having a conductor thatis at least partially surrounded by a conductive polymer and acontinuous, non-braided, non-conductive polymer covering that at leastpartially surrounds said conductive polymer, said continuous,non-braided, non-conductive polymer covering being porous to water andpermitting water to electrically contact said conductive polymer;installing said water detection cable adjacent to a surface that is tobe monitored for the presence of water; providing a monitor formonitoring said water detection cable; and generating a signal upondetection of water.
 8. The method of claim 7 wherein said step ofmonitoring said water detection cable comprises monitoring said waterdetection cable using a Time Domain Reflectometry water detectionmonitoring system.
 9. The method of claim 7 wherein said step ofmonitoring said water detection cable comprises monitoring said waterdetection cable using a resistive measurement water detection monitoringsystem.
 10. The method of detecting water of claim 7 wherein said watertransmission path is provided by pores in said continuous, non-braided,non-conductive polymer covering.
 11. A method of detecting watercomprising: providing a water detection cable that has at least twosensing leads, said sensing leads having a resistive conductor that isat least partially surrounded by a continuous, non-braided,non-conductive polymer covering that is porous to water, said continuousnon-conductive polymer coating that is porous to water providing a watertransmission path that permits water to electrically contact saidconductor; installing said water detection cable adjacent to a surfacethat is to be monitored for the presence of water; providing a monitorfor monitoring said water detection cable; and generating a signal upondetection of water.
 12. The method of detecting water of claim 11wherein said water transmission path is provided by pores in saidcontinuous, non-braided, non-conductive polymer covering.
 13. A methodof constructing a water detection cable comprising: providing a firstsensing lead that has a conductor that is at least partially surroundedby a conductive polymer that is at least partially surrounded by acontinuous, non-braided, non-conductive polymer covering that is porousto water; providing a non-conductive polymer spacing member, saidspacing member being joined to said first sensing lead along alongitudinal axis of said first sensing lead; and providing a secondsensing lead that has a conductor that is at least partially surroundedby a conductive polymer that is at least partially surrounded by acontinuous, non-braided, non-conductive polymer covering that is porousto water, said second sensing lead being joined to said non-conductivepolymer spacing member along a longitudinal axis of said non-conductivepolymer spacing member.
 14. A water detection cable comprising: a firstsensing lead that has a conductor that is at least partially surroundedby a conductive polymer and a non-conductive polymer that at leastpartially surrounds said conductive polymer, said non-conductive polymerproviding an insulating layer at least partially surrounding saidconductive polymer; a non-conductive polymer spacing member adjacent andjoined to said sensing lead; a second sensing lead that has a conductorand is at least partially surrounded by a non-conductive polymer, saidnon-conductive polymer having a thickness and a dielectric constant thatpermits the presence of water to be detected by detecting a change inthe dielectric constant at the location of said water, said secondsensing lead and said first sensing lead adjacent and joined to saidspacing member so as to form a trough that is capable of collectingwater; and a non-conductive polymer cover that partially covers saidconductive polymer of said first sensing lead such that watertransmission path that allows water to electrically contact saidconductive polymer of said first sensing lead is provided between saidnon-conductive polymer cover and said non-conductive polymer spacingmember.
 15. A substantially flat four-conductor water detection cablecomprising: a first sensing lead that has a conductor that is at leastpartially surrounded by a conductive polymer and a non-conductivepolymer shielding that at least partially surrounds said conductivepolymer of said first sensing lead; a first non-conductive polymer coverthat partially covers a portion of said conductive polymer of said firstsensing lead so that said first non-conductive polymer cover and saidnon-conductive polymer shielding form at least one trough, said troughproviding a water transmission path that allows water to electricallycontact said conductive polymer by passing between said non-conductivepolymer shielding and said non-conductive polymer cover, saidnon-conductive polymer shielding and said non-conductive polymer coverpositioned so that electrical contact of a solid object with saidconductive polymer is inhibited; a second sensing lead that has aconductor that is at least partially surrounded by a conductive polymerand said non-conductive polymer shielding that at least partiallysurrounds said conductive polymer of said second sensing lead; a secondnon-conductive polymer cover that at least partially covers a portion ofsaid conductive polymer of said second sensing lead so that said secondnon-conductive polymer cover and said non-conductive polymer shieldingform at least one trough, said trough providing a water transmissionpath that allows water to electrically contact said conductive polymerby passing between said non-conductive polymer shielding and said secondnon-conductive polymer cover, said non-conductive polymer shielding andsaid second non-conductive polymer cover positioned so that electricalcontact of a solid object with said conductive polymer is inhibited.